New REVIT 2013 Sky Background.
I like the new Sky option in REVIT 2013. When you first turn it not you may not see anything until you have the Sky (above horizon line / Level 1) in your view. You need to be looking 'Up' to see the sky.
The resulting sky is impacted by the Sun settings for Azimuth and Altitude. So the higher the sun is in the sky the lighter the sky will be. Give at a whirl.
This effect is located in the view's 'Graphic Display Option' dialog box as a view property. You can also set the color of the space below the horizon line (shown in Green). Why not take the extra step and save the View Template. Keep in mind that the view templates now update the views instantly like everything else in REVIT. HUGE !
The Sky functionality is available in Elevation, Section, Isometric, and Perspective 3D views. Also the background options are available in Hidden Line, Shaded, Consistent Colors and Realistic visual styles.